1. Field of the Invention
The present invention relates to a vacuum treatment system for vacuum coating/deposition. Particularly, the present invention relates to a drive mechanism for a vacuum coating/deposition systems.
2. Description of the Prior Art
Electron beam evaporation is one method of physical vapor deposition for integrated circuit lift-off processes and optical coatings. Electron beam evaporation may be used to deposit a thin metal layer on a semiconductor wafer or other substrate. The deposited metal layer may be subsequently etched to create circuit traces of integrated circuits.
Various systems have been developed using physical vapor deposition techniques. Some systems are linear systems where the target product (the substrate) is affixed to a carrier that is linearly brought into a vacuum chamber along a set of rails where the deposition apparatus, i.e. the electron gun, is located. Once the desired deposition has occurred, the target product is then moved linearly along to an exit port or returned to the entrance port for removal from the vacuum deposition system. These systems employ mechanical drive systems such as drive belts or gears or drive tapes to move the carrier containing the substrate through the vapor deposition system.
There have also been developed systems that provide greater throughput of the substrate while achieving more highly-uniform deposits of metal layers on the substrate(s). To improve uniformity, manufacturers have developed an evaporation system having multiple substrate support trays that rotate about their axes while also moving in a circle around the outside of a central drive ring. One such system, known as a high uniformity lift-off assembly (HULA), features a central drive ring with teeth/gears around its perimeter. The system also has smaller rotating substrate holders/carriers positioned around the perimeter of the central ring. As the outer rings move around the perimeter of the central ring, teeth on the perimeters of the outer rings engage the teeth on the central ring, causing the outside rings to also rotate about their central axes. In some systems, the drive ring may have gears located near the hub that are linked to gears or teeth on secondary rings. Using teeth, gears, or other features located on a primary ring and on secondary rings is an example of a positive drive mechanism.
An alternative to the above-disclosed mechanical drive systems, there has been developed drive systems that incorporate the use of a magnetic drive/transfer system. This magnetic transfer system is provided with a rotational driving member which is divided into two portions serving as a fixed driving shaft and a movable driving shaft in the axial direction and in which the fixed driving shaft is secured to a shaft core member so as to be limited in the rotational direction but so as to be freely movable in the axial direction at a certain width. Spiral magnetic coupling sections are formed on the surface of each driving shaft at the same pitch. The carrier can be freely moved against the surface of the rotational driving member in its axial direction and is provided with magnetic coupling sections at an interval equal to a pitch in the spiral magnetic coupling sections. By rotating the rotational driving member, the carrier linearly moves.
One example of a rotational system is disclosed in U.S. Pat. No. 6,454,908 (Shertler et al., 2002). Shertler et al. disclose a vacuum chamber in which there is at least one part that is driven in rotation and is connected by a gear train. The gear train has at least two rotating transmission bodies with a motor drive unit. The rotating transmission bodies produce relative motion in a rolling manner. The rotating transmission bodies are magnetically drive-coupled to each other, and at least one of them is located in the vacuum chamber.